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[bil-yuh n] /ˈbɪl yən/
noun, plural billions (as after a numeral) billion.
a cardinal number represented in the U.S. by 1 followed by 9 zeros, and in Great Britain by 1 followed by 12 zeros.
a very large number:
I've told you so billions of times.
equal in number to a billion.
Origin of billion
1680-90; < French, equivalent to b(i)- bi-1 + -illion, as in million
Related forms
billionth, adjective, noun Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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British Dictionary definitions for billionth


noun (pl) -lions, -lion
one thousand million: it is written as 1 000 000 000 or 109
(formerly, in Britain) one million million: it is written as 1 000 000 000 000 or 1012
(often pl) any exceptionally large number
(preceded by a or a cardinal number)
  1. amounting to a billion: it seems like a billion years ago
  2. (as pronoun): we have a billion here
Derived Forms
billionth, adjective, noun
Word Origin
C17: from French, from bi-1 + -llion as in million
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for billionth

1778, from billion + -th (2).



1680s, from French billion (originally byllion in Chuquet's unpublished "Le Triparty en la Science des Nombres," 1484; copied by De la Roche, 1520), from bi- "two" (see bi-) + (m)illion. A million million in Britain and Germany (numeration by groups of sixes), which was the original sense; subsequently altered in French to "a thousand million" (numeration by groups of threes) and picked up in that form in U.S., "due in part to French influence after the Revolutionary War" [David E. Smith, "History of Mathematics," 1925]. France then reverted to the original meaning in 1948. British usage is truer to the etymology, but U.S. sense is said to be increasingly common there in technical writing.

Online Etymology Dictionary, © 2010 Douglas Harper
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